Many types of electronic devices, such as interactive computers and acoustic devices, provide services to nearby users. In the absence of a user, these electronic devices are typically in a standby mode to save power consumption. Since it is inconvenient to request a user to perform some operations when beginning and/or resuming the use of an electronic device, efforts have been made to use various sensors for enabling a device or system to detect the presence of a user.
Japanese Patent Application Publication No. 2016-039447 describes a technique for preventing an image output device from transitioning to a power saving mode regardless of the presence of a nearby user using the image output device. This technique uses an infrared array sensor to switch power modes.
Japanese Patent Application No. 2014-72523 describes a flow sensor. Here, the flow sensor includes a heater element and a pair of temperature sensor resistive elements disposed on both sides of the heater element.
Japanese Patent Application No. 2007-285996 describes a thermal sensitive acceleration sensor. Here, the thermal sensitive acceleration sensor includes two pairs of temperature detecting elements sandwiching a heater in closed space that detects temperature differences caused by acceleration.
Active-type user detection sensors that emit infrared rays, ultrasonic waves, light, or the like toward a human to detect the presence of a human based on a response thereof, consume large amounts of power. A user detection sensor using a camera also consumes a large amount of power. In addition, the use of a camera for user detection often tends to be unfavorable by users for privacy reasons. Further, some user detection sensors may not be effective because they are only capable of detecting a human within a limited range and/or direction.